Credit: Kevin Redding, Arizona State University, and Pixabay
Type I and Type II reaction centers use light to drive electron transfer as part of natural photosynthesis. Researchers compared the structures of four centers: the Heliobacterial reaction center (HbRC; green), the purple bacterial reaction center (PbRC, red), and plant Photosystem I (PSI, blue) and Photosystem II (PSII, yellow). Among the explained structural differences are the distance between the starting point for electron transfer and the first electron acceptor and the orientation of an electron transfer intermediate (noted by different abbreviations).